Putter head with pre-machined insert

ABSTRACT

The invention provides a head for a putter. The face of the putter head includes very shallow markings having a depth of the order of 50 microns (0.05 mm). The markings are formed on an insert defining the sweet spot of the putter face by an end milling process with the insert being resiliently supported and fixed within a cavity in the head by means of resilient O-rings. Since the resilient O-rings take up any clearance the insert does not need to be made to tight tolerance and can be machined out with the head prior to insertion within the head cavity. The markings produced are radial and non-concentric grooves.

[0001] This invention relates to a head for a golf putter. Moreparticularly the invention is concerned with producing a head for aputter in such a manner as to allow expensive machining techniques to beused to provide the face of the putter with markings designed tofacilitate the control of a golf ball during the putting stroke.Preferably the markings are confined to the sweet spot on the putterface.

[0002] In U.S. Pat. No. 5,275,409 (Currie-1994) there is disclosed aputter having a vertical flat machined surface extending between top andbottom surfaces. The vertical flat machined surface forms the strikingface of the putter. According to this patent the process of machiningprovides a technique in which a very flat surface can be provided upon aputter head. However this patent laments the fact that machined putterheads are not common and have not been widely adopted because themachining process is so expensive.

[0003] U.S. Pat. No. 3,206,206 (Santosuosso-1965) discloses a putterhead having a rectangular insert fitted within the putter head. Theinsert is grooved for contacting the ball. However, this design likewisedoes not seem to have gained wide acceptance in the art possibly becauseof the complexities of machining the rectangular opening in the putterhead and then machining the insert to fit within the opening.

[0004] In U.S. Pat. No. 5,637,044 (Swash) a putter head is disclosedhaving concentric grooves with a commom centre of rotation formed on theface of the putter. The grooves are described as being relativelyshallow but even so have a depth typically of between 0.2 to 0.3 mm. Thegrooves are said to impart advantageous spin to the ball.

[0005] According to the present invention there is provided a head for aputter, the head including a striking face having markings formed on atleast a part of the putter face, the markings being of micron size.

[0006] Preferably the markings are curvilinear and non-concentric andare formed by a machining process, for example, a milling process. Amilling cutter, for example an end mill may be passed over the surface.

[0007] The invention will now be described by way of example only withreference to the accompanying drawings wherein:

[0008]FIG. 1 shows a front perspective view of a putter head inaccordance with one aspect of the invention.

[0009]FIG. 2 shows a front perspective view of a putter head inaccordance with a second aspect of the invention

[0010]FIG. 3 shows a part sectional elevation of the putter head shownin FIG. 2.

[0011]FIG. 4 is a perspective view of an insert for insertion into aputter head in accordance with the invention.

[0012]FIG. 5 illustrates the curvilinear markings that may be formedupon the putter face in accordance with the invention.

[0013]FIG. 6 illustrates a part cross-section of markings in accordancewith the invention.

[0014] In FIG. 1 there is shown a putter head 2 in accordance with afirst aspect of the invention. A shaft 3 is attached to putter head 2,for example by suitable adhesive. Putter head 2 includes curved sidesurfaces 4, 5 and a curved rear surface 6 and has a striking face 7.

[0015] Dotted lines 8 denote an area including the sweet spot on theputter face 7 and has curvilinear surface markings 9 formed thereon bythe machining method described below.

[0016] In FIG. 2 there is shown a golf putter 10 in accordance with asecond aspect of the present invention. Golf putter 10 comprises aT-shaped head 11 connected to a shaft 12 by means of a hosel member 13.Hosel member 13 may be hollow as best seen in FIG. 3. A shaft connectionmay comprise the hosel member 13 or the hosel member 13 may be dispensedwith and the shaft connection may comprise shaft 14 connected directlyto head 11. A reinforcing ring 13A may be used to assist in connectingshaft 14 to hosel member 13. The head 11 comprises an outer shell member15, best seen in FIG. 3 which defines a closed cavity 16 within head 11.A shoulder 17 is formed within the cavity 16. The putter head 11includes a striking face 18. An important part of the present inventionis the use of an elongate cylindrical inner insert member 19 set into orlocated within cavity 16 in the head 11. As seen in FIG. 4 inner insertmember 19 has a front face 20 and a rear face 21 and a circularperipheral surface 22 joining the front and rear surfaces 20, 21.Peripheral surface 22 has two semi-circular grooves 23, 24 formedthereon for a purpose later to be explained. An aperture 25 is formed ininsert 19 by drilling and reaming to receive and ensure a proper fit foreither hosel 13 or shaft 14. As best seen in FIG. 3 hosel member 13stops short of the end of the aperture 25 so that it does not contactthe outer shell member 15. It is believed this arrangement enhances thetransmission of impact energy to the putter shaft as “feel”. A sweetspot 26 for the putter head 11 as indicated by the crossed lines 27 isarranged to be at the centre of area of the front face 20 of insert 19.Insert 19 is supported and fixed within cavity 16 by means of Neopreneresilient O-rings 28, 29 (see FIG. 3) fitted to the semi-circulargrooves 23, 24 in the insert 19. A small clearance is left between theshoulder 17 in the cavity 16 and the rear face 21 of insert 19. Also asbest seen in FIG. 3 the O-rings 28, 29 space the insert 19 from theouter shell member 15 so that a small clearance 30 is formed between theperiphery 22 of insert 19 and the outer shell member 15. Thus this in asense insulates the insert member from the outer shell member so thatimpact energy is channelled directly through the insert member 19 tohosel 13 and hence up shaft 14 to be felt as “feel” in the golfer'shands. The rear surface 21 defines a blind bore or cavity 31 whichtogether with the remainder of cavity 16 forms a void 32 within the head11. This is thought to increase the resonance factor of the head therebycontributing to the “feel” of the putter. Stabilising or inertia weights33 are let into the sides 34 of head 11 to minimise the effect ofoff-centre hits. A slot 35, see FIG. 2, assists in aiming the strikingface 18 of the putter. In addition to resiliently fixing insert 19within cavity 16 the O-rings act as seals to prevent dirt and moisturefrom entering through clearance 30 and acting on either side of theshaft connection 13 within cavity 25 they also protect this assembly.Shaft connection 13 enters aperture 25 in insert 19 through a drilledhole 36 in outer shell member 15.

[0017] The arrangement whereby insert 19 is located within cavity 16 bymeans of the resilient O-rings 28, 29 and thereby forms a part ofstriking face 18 provides a number of important advantages. For example,it means that the round peripheral surface 22 of insert 19 need not bemade to tight tolerances, indeed it need not be machined atall with theresult that insert 19 may be made from bar stock. Likewise since therear surface 21 stops short of shoulder 17 within cavity 16 this neednot be made to tight tolerances. Indeed since the rear surace 21 ishidden from view within the cavity 16 the end of the insert 19 need notbe machined atall and may have an as-cut finish or as-cast finish as thecase may be. Any discrepancies in fit can be taken up by the resilienceof the O-rings This means that it is the front surface 20 only formingthe sweet spot that needs to be subjected to the expense of a machiningprocedure. Also the fact that the insert 19 can be pre-machined out withcavity 16 and prior to installation therein means that the machiningprocedure can be considerably simplified.

[0018]FIG. 5 shown greatly exaggerated for ease of explanationillustrates the characteristics of the surface markings formed on thesweet spot 26 on insert 19. As shown these are non-concentriccurvilinear grooves having the cross-section shown in FIG. 6 with apitch (P) of 0.7 mm. The grooves or markings illustrated in FIG. 6 areof Micron size (1 micron=1 thousandth of 1 mm). As used herein the term“micron size ” is meant to convey the meaning of a depth (D) of markingsor grooves several orders smaller than the smallest groove (0.2 mm)disclosed in the above mentioned U.S. Pat. No. 5,637,044 (Swash). Thatis a depth (D) of 0.05 mm (50 microns) to 0.1 mm for the presentinvention compared to depth of 0.2 mm in the Swash patent. In apractical embodiment of the present invention with an insert diameter of25.4 mm a tungsten carbide end mill of 62 mm diameter was passed onceover the front surface of the insert. End mills having a diameter ofbetween 25 and 76 mm could be used in the practise of the invention. Thecurvilinear non-concentric markings produced by the end milling are ofconstant radius and present the same configuration to the golf ball asit moves relative to the putter face during a putting stroke. This is incontrast to the aforementioned Swash patent where the grooves radiatingfrom a common centre point will result in presenting differingconfigurations to the golf ball. Also grooves or markings of this smallorder of depth could possibly allow face slippage if the putt is at anangle from the desired path of travel but the lightly curved lines willhave a slightly self centralising effect.

[0019] The insert member 19 is made from a material selected to be asoft ductile material, for example bronze, which will facilitate thetransmission of shock thereby conveying impact energy as “feel” to thegolfer's hands. Outer shell member 15 and hosel member 13 are made ofaircraft quality high strength aluminium (specification-6082T6 (H30).The putter head of the present invention may be used with anyconventional shaft but it can be most advantageously used in a putterwith a substantially large diameter (between 25 and 45 mm), thin walled(between 0.75 and 1 mm), parallel shaft or a grip made therefrom toenhance the “feel” thereof. then such large sized shaft or grip is usedthe preferred material is carbon fibre.

1. A head for a putter, the head including a striking face havingmarkings formed on a part of the striking face, the markings being ofmicron size.
 2. A head for a putter according to claim 1 wherein themarkings have a depth of 50 microns (0.05 mm)
 3. A head for a putteraccording to claim 2 wherein the markings are V-shaped grooves having apitch of 0.7 mm.
 4. A head for a putter according to claim 1 wherein themarkings are curvilinear and non-concentric.
 5. A head for a putteraccording to claim 1 wherein the markings are formed on an insertlocated within a closed cavity formed within the head.
 6. A head for aputter according to claim 5 wherein the insert is spaced from the headby means of a clearance space.
 7. A head for a putter according to claim6 wherein the insert is made from bar stock material.
 8. A head for aputter according to claim 6 wherein the insert is made from as castmaterial.
 9. A head for a putter according to claim 7 or claim 8 whereinthe insert has a front face, the front face only being machined fromeither the bar stock or as cast material.
 10. A head for a putteraccording to claim 1 wherein the markings are produced by means of amilling process.
 11. A head for a putter according to claim 10 whereinthe milling process uses an end mill.
 12. A head for a putter accordingto claim 5 wherein the insert defines the sweet spot of the putter. 13.A head for a putter substantially as herein described with reference toany one of FIGS. 1 to 6 of the accompanying drawings.
 14. An insert fora putter head, the insert having markings formed on a face thereof, themarkings being of micron size.
 15. An insert for a putter head accordingto claim 14 wherein the markings have a depth of 50 microns (0.05 mm)16. An insert for a putter head according to claim 14 wherein themarkings are curvilinear and non-concentric.
 17. An insert for a putterhead substantially as herein described with reference to FIG. 4 of theaccompanying drawings.